This disclosure provides methods and apparatus, including computer-readable media, for wireless power transfer and particularly active cancellation of undesirable electric or magnetic field emissions from a wireless power transmitter. In one aspect, the disclosure provides for an apparatus including a sensor, controller, and emitter, wherein the sensor is used to sense the electric or magnetic field emissions from a transmit antenna, the controller configured to determine the undesirable components of the field, and the emitter to generate a field to destructively interfere with the undesirable components.